Step 1: Cook the tortellini according to package instructions in a large pot of salted boiling water until al dente. Reserve about 1 cup of pasta water before draining.
Step 2: While the tortellini cooks, pat the peeled and deveined shrimp dry with paper towels. Season them generously with salt, black pepper, and a pinch of red pepper flakes (if desired). Heat 1 tablespoon of olive oil in a large skillet or Dutch oven over medium-high heat. Add the seasoned shrimp in a single layer and cook for 1-2 minutes per side, until pink and opaque. Remove the shrimp from the skillet and set aside.
Step 3: Reduce the heat to medium. Add the remaining 1 tablespoon of olive oil (or butter) to the same skillet. Add the minced garlic and sauté for about 30 seconds until fragrant, being careful not to burn it.
Step 4: Pour in the heavy cream and chicken broth. Bring the mixture to a gentle simmer, stirring occasionally. Allow it to simmer for 3-5 minutes, or until the sauce begins to slightly thicken.
Step 5: Stir in the freshly grated Parmesan cheese until it melts and the sauce is smooth and creamy. If the sauce seems too thick, add a splash of the reserved pasta water, a tablespoon at a time, until it reaches your desired consistency. Taste and adjust seasonings.
Step 6: Add the fresh baby spinach to the skillet. Stir gently until the spinach wilts down, which should only take about 1-2 minutes.
Step 7: Return the cooked shrimp and drained tortellini to the skillet with the creamy sauce and spinach. Toss everything gently to combine. Heat through for another minute or two.
Step 8: Serve immediately, garnished with extra Parmesan cheese and fresh parsley or basil, if desired.